Gas turbine-two-stroke piston compound engine

Abstract

A compound engine including a gas turbine unit and a two-stroke uniflow scavenge piston unit having a hollow cylindrical exhaust valve mounted concentrically with an associated piston to form a portion of the combustion chamber within a peripheral wall of the exhaust valve. A double acting exhaust valve actuator is responsive to rotation of the crankshaft and is operatively coupled to the peripheral wall of the hollow cylindrical exhaust valve to produce forces derived directly from rotation of the crankshaft to open and close the exhaust valve. The actuator is a camshaft having two sets of cams which drive a cam follower in response to rotation of the crankshaft.

What is claimed is: 
     
       1. A compound engine comprising: a gas turbine unit including a compressor receiving ambient air for providing cycle air,   a thermal reactor receiving the cycle air and providing cycle gas to first and second outlets of the thermal reactor,   a first turbine connected to and driving the compressor, the first turbine receiving cycle gas from the second outlet of the thermal reactor, and   a second turbine having an input fluidly coupled to an output of the first turbine; and     a two-stroke uniflow scavenge piston unit having an intake in fluid communication with the first outlet of the thermal reactor,   a crankshaft mechanically coupled to the second turbine,   a camshaft operatively coupled to the crankshaft and rotating in synchronization with the crankshaft;   a plurality of piston and cylinder units, each of the piston and cylinder units having a piston mounted for sliding motion within a respective cylinder and operatively connected to the crankshaft,   a hollow cylindrical exhaust valve mounted concentrically with the piston at one end of the respective cylinder, the exhaust valve being mounted for sliding motion with respect to an inner surface of a respective piston and cylinder unit, and the exhaust valve being in fluid communication with the second outlet of the thermal reactor,     a double acting exhaust valve actuator responsive to rotation of the camshaft and operatively coupled to an annular body of the hollow cylindrical exhaust valve, the exhaust valve actuator producing a first force derived directly from rotation of the camshaft to open the exhaust valve, the first force being applied to the annular body of the exhaust valve in a direction substantially away from the crankshaft, and   producing a second force derived directly from rotation of the camshaft to close the exhaust valve, the second force being applied to the annular body of the exhaust valve in a direction substantially toward the crankshaft.       
     
     
       2. The compound engine of claim 1 wherein the double acting exhaust valve actuator comprises: a first cam surface on the camshaft associated with opening the exhaust valve;   a second cam surface on the camshaft associated with closing the exhaust valve; and   a follower unit simultaneously contacting the annular body of the exhaust valve and of the first cam surface and the second cam surface, the cam follower unit translating longitudinally to provide the opening and the closing of the exhaust valve in response to rotation of the camshaft.   
     
     
       3. The compound engine of claim 2 wherein the second cam surface comprises a pair of cam surfaces, each of the pair of cam surfaces being located on one side of one of the first cam surface. 
     
     
       4. The compound engine of claim 3 wherein the cam follower unit further comprises a pair of connecting links, each of the connecting links being connected to a member on one side of the peripheral wall of the exhaust valve and having an opening at an opposite end for receiving the cam shaft. 
     
     
       5. The compound engine of claim 4 wherein the cam follower unit further comprises: a first cam follower mounted proximate the one end of the pair of connecting links and contacting the first cam surface; and   a second cam follower mounted proximate the opposite end of the pair of connecting links and contacting the second cam surface.   
     
     
       6. The compound engine of claim 5 wherein the cam follower unit further comprises: a first shaft extending between and connected to the one end of the pair of connecting links; and   a second shaft extending between and connected to the other end of the pair of connecting links.   
     
     
       7. The compound engine of claim 6 wherein the first cam surface is mounted on the first shaft and the second cam surface is mounted on the second shaft. 
     
     
       8. The compound engine of claim 1 wherein the compressor and the first turbine are a high pressure compressor and a high pressure turbine, respectively, and the second turbine is a low pressure turbine. 
     
     
       9. A compound engine comprising: a gas turbine unit including a high pressure compressor having an input receiving ambient air and having a compressor output providing cycle air at a pressure substantially greater than atmospheric pressure,   a thermal reactor having a first input fluid passage connected to the compressor output for conducting the cycle air through the thermal reactor,   a first outlet in fluid communication with the first input fluid passage for exiting a first portion of the cycle air from the thermal reactor,   a second outlet,   a heater selectively activated during operation of the compound engine and in fluid communication with a second portion of the cycle air to provide heated working gas to the second outlet,   a second inlet fluid passage connected directly with the second outlet,     a high pressure turbine connected to and driving the high pressure compressor, the high pressure turbine having an inlet fluidly coupled to the second outlet of the thermal reactor, and   a low pressure turbine having an input fluidly coupled to an outlet of The high pressure turbine, the low pressure turbine further having an output shaft; and     a two-stroke diesel piston unit having a plurality of pistons,   a plurality of Scotch yokes, each of the plurality of Scotch yokes being operatively connected to two of the plurality of pistons,   a crankshaft rotatably connected to the plurality of Scotch yokes and mechanically coupled to the output shaft of the low pressure turbine, the crankshaft providing a mechanical output from the compound engine,   a plurality of cylinders, each of the plurality of cylinders slidably receiving one of the plurality of pistons and each of the plurality of cylinders further including, a cycle air intake opening in a wall of the cylinder at a location above a bottom dead center position of the piston, the cycle air intake opening being in fluid communication with the first outlet of the thermal reactor;   a hollow cylindrical exhaust valve mounted concentrically with a respective one of the pistons above a top dead center position of the respective piston, the exhaust valve providing an exhaust gas outlet for the cylinder and being in fluid communication with the second inlet fluid passage of the thermal reactor,     a camshaft connected to the crankshaft and rotating in synchronization with the crankshaft, the camshaft having a first cam having a first cam surface providing a first camming action in a direction away from the crankshaft to open the exhaust valve, and   a second cam having a second cam surface providing a second camming action in a direction toward the crankshaft to close the exhaust valve,     a cam follower unit operatively connected to an annular body of the exhaust valve and contacting the first and second cam surfaces, the cam follower unit translating longitudinally to open the exhaust valve in response to a translation away from the crankshaft and to close the exhaust valve in response to a translation toward the crankshaft in response the first and the second camming actions, respectively.     
     
     
       10. A method of starting a compound engine having a gas turbine unit including a compressor receiving ambient air for providing cycle air,   a thermal reactor receiving the cycle air through a first inlet and providing a first portion of the cycle air to a first outlet of the thermal reactor, the thermal reactor including a burner in fluid communication with the cycle air to provide heated working gas to a second outlet of the thermal reactor, and   a first turbine connected to and driving the compressor, the first compressor connected to the second outlet of the thermal reactor,   a second turbine having an input fluidly coupled to an outlet of the first turbine, and   a two-stroke uniflow scavenge piston unit having an air intake in fluid communication with the first outlet of the thermal reactor,   a crankshaft mechanically coupled to the second turbine,     a camshaft operatively coupled to the crankshaft and rotating in synchronization with the crankshaft; a plurality of piston and cylinder units operatively connected to the crankshaft, each of the piston and cylinder units having a piston mounted for sliding motion within a respective cylinder and operatively connected to the crankshaft,   a hollow cylindrical exhaust valve mounted concentrically with the piston at one end of the respective cylinder the exhaust valve being mounted for sliding motion with respect to an inner surface of a respective piston and cylinder unit, and the exhaust valve being in fluid communication with a second inlet of the thermal reactor,     a double acting exhaust valve actuator responsive to rotation of the camshaft and operatively coupled to an annular body of the hollow cylindrical exhaust valve, the exhaust valve actuator, the method comprising: directing cycle air from the compressor to the thermal reactor;   injecting fuel into the thermal reactor;   igniting and burning the fuel in the thermal reactor, thereby rotating the first turbine, the second turbine and the crankshaft to reciprocate pistons within the plurality of piston and cylinder units;   moving the hollow cylindrical exhaust valve to an open position in response to a first force derived directly from the rotation of the camshaft and applied to the annular body of the exhaust valve in a direction substantially away from the crankshaft; and   moving the hollow cylindrical exhaust valve to a closed position in response to a second force derived directly from the rotation of the camshaft and applied to the annular body of the exhaust valve in a direction substantially toward the crankshaft.